This invention relates to an exposure device used to print/expose a negative image on a negative film on a photosensitive material.
As an exposure device, the one shown in FIG. 5 is known. In this exposure device, a photosensitive material P drawn from a roll R is cut to a predetermined size by a cutter device 30. The photosensitive material P1, which is now cut off, is supported on an exposure table 20. A negative film F is illuminated by a light source 21 to print/expose the negative image thereon on the photosensitive material P1 through a printing lens 22.
As shown in FIG. 6, the exposure table 20 in the exposure device comprises a motor 23, an endless suction belt 24 driven by the motor 23 and formed with a plurality of suction holes 25, a suction box 26 having a support plate 27 formed with a plurality of suction holes 28, which are communicable with the suction holes 25 of the suction belt 24, and a blower 29 for suctioning the interior of the suction box 26. The photosensitive material P1 is suctioned and kept in its position by a suction force applied through the suction holes 28 and the suction holes 25 until it is fed to the exposure stage to be printed and exposed.
Furthermore, the photosensitive material P1, after being printed and exposed, is fed from the exposure table 20 to a developing unit (not shown) by the movement of the suction belt 24.
In such a conventional exposure device, the suction force is applied through all of the suction holes 25 of the suction belt face 24a regardless of the width of the photosensitive material P1. If it has a small width, so many suction holes 25 are open that air is also sucked into the suction box 26 through the suction holes 25.
Thus, the suction force per unit surface area of the photosensitive material P1 becomes so weak that the material is not suctioned enough and becomes adrift. This will cause a fuzziness problem.
If the suction force is set based on the smallest width of the photosensitive material P1 to in order to solve this problem, it is necessary to provide a blower 29 of an extremely large capacity, resulting in the problem of noise. Moreover, the suction belt 24 then has a larger transfer resistance, which will increase the size of the motor 23 as well as the cost.